Flow and heat transfer analysis of submerged multiple synthetic jet impingement in a square channel with forced-flow

This study experimentally and numerically investigated the flow and heat transfer of submerged multiple synthetic jet impingement in forced crossflow in a square-section channel with a constant heat flux on the bottom surface. In the forced channel flow, effects on heat transfer of six synthetic jets placed diagonally in the main flow have four different amplitudes and six different frequencies at various Reynolds numbers (6000 <= Re <= 40000) were examined. Jets were submerged vertically into the main flow and their effects on heat transfer in the turbulent regime of the main flow were analyzed. Temperature measurements were made using thermocouples placed at the channel entrances and exits on the target surface. The Nusselt numbers (Nu) were calculated using the measured temperatures. The results indicate that at Re = 6000, the target surface temperature decreases significantly with increasing amplitude and frequency, and the effects of amplitude and frequency on surface temperatures decreased at increasing Reynolds numbers. It was observed that the THP values increased with increasing amplitude and frequency for all Reynolds numbers tested. For a constant jet parameter (Ao = 0.88 and Wo = 27), the highest THP was determined as 2.06 at Re = 6000.